Aluminum or magnesium would make the most sense if you are sure they were metal. Still a little odd to hear that.
The Ferrari F50 has a very similar intake design - those exact same parts are plastic and (except for being paired) look nearly identical. There's a thread on FChat with descriptions and photos:
http://www.ferrarichat.com/forum/showthread.php?t=69507
>8^)
ER